diff --git a/backend/src/services/services.service.ts b/backend/src/services/services.service.ts
index 2ddd08b..f96bf11 100644
--- a/backend/src/services/services.service.ts
+++ b/backend/src/services/services.service.ts
@@ -36,6 +36,50 @@ export class ServicesService {
     if (!prof) prof = await this.prisma.professionals.findUnique({ where: { user_id: data.professional_id } });
     if (!prof || !prof.is_active) throw new BadRequestException('Profesional no disponible');
 
+    if (data.range1_hour1) {
+      const slotTime = new Date(`1970-01-01T${data.range1_hour1}:00`);
+
+      // Double-booking check: reject if this slot already has a non-cancelled/denied service
+      const conflict = await this.prisma.services.findFirst({
+        where: {
+          professional_id: prof.id,
+          day: new Date(data.day),
+          range1_hour1: slotTime,
+          status: { notIn: ['denied', 'cancelled'] },
+        },
+      });
+      if (conflict) throw new BadRequestException('Este horario ya está ocupado');
+
+      // Schedule validation: confirm the slot is within the professional's configured hours
+      // JS getDay() → 0=Sun…6=Sat; DB convention → 0=Mon…6=Sun, so: (getDay()+6)%7
+      const jsDay = new Date(data.day).getDay();
+      const dayOfWeek = (jsDay + 6) % 7;
+      const schedule = await this.prisma.schedules.findFirst({
+        where: { professional_id: prof.id, day_of_week: dayOfWeek, enabled: true },
+      });
+      if (!schedule) throw new BadRequestException('El profesional no atiende ese día');
+
+      const toMins = (d: Date | null) => d ? d.getUTCHours() * 60 + d.getUTCMinutes() : null;
+      const [sh, sm] = data.range1_hour1.split(':').map(Number);
+      const reqMins = sh * 60 + sm;
+
+      let inRange = false;
+      if (schedule.continuous_day) {
+        // Full day: range1_hour1 → range2_hour2
+        const start = toMins(schedule.range1_hour1);
+        const end   = toMins(schedule.range2_hour2);
+        if (start !== null && end !== null) inRange = reqMins >= start && reqMins < end;
+      } else {
+        // Morning block: range1_hour1 → range1_hour2
+        const s1 = toMins(schedule.range1_hour1), e1 = toMins(schedule.range1_hour2);
+        if (s1 !== null && e1 !== null) inRange = inRange || (reqMins >= s1 && reqMins < e1);
+        // Afternoon block: range2_hour1 → range2_hour2
+        const s2 = toMins(schedule.range2_hour1), e2 = toMins(schedule.range2_hour2);
+        if (s2 !== null && e2 !== null) inRange = inRange || (reqMins >= s2 && reqMins < e2);
+      }
+      if (!inRange) throw new BadRequestException('La hora seleccionada está fuera del horario del profesional');
+    }
+
     return this.prisma.services.create({
       data: {
         professional_id: prof.id,