Postoperative pain is a subjective symptom that has been extensively studied in adults, but only minimally in children. In children, use of low analgesic doses and failure to document the pain and its management are common concerns. In newborns and infants pain is difficult to interpret. This was a double-blind, prospective, multicenter observational study conducted in four public Mexican hospitals to identify analgesic use. One hundred subjects were enrolled at each institution and monitored for 24 to 48 hours following surgery. Data were collected on 152 girls and 248 boys ranging in age from newborns to 14 years. Nearly 300 (290) underwent major procedures; 110 had short stay surgery. The most common analgesics used were paracetamol and dipyrone at low doses. Less frequently ibuprofen or another anti-inflammatory was used. Many children received no analgesic, including 30 newborns, and others received only one or two analgesic doses. Fifteen burn patients received ketorolac. The occurrence and characteristics of the pain were poorly documented in all four hospitals. Postoperative pain causes suffering and can prolong hospital stays. Graphic pain intensity scales exist to evaluate pain, but use of them was not documented in medial records. Nurses and doctors in training did not have the skills needed to evaluate pain. The study revealed errors in pain management and fear among staff in using high doses of common analgesics. The study results document patterns of care in most Mexican hospitals today and indicate a need for pain management training for Mexican doctors and nurses.