The Multi-Country Evaluation of Integrated Management of Childhood Illness (IMCI) Effectiveness, Cost and Impact (MCE) was launched to assess the global effectiveness of this strategy. Impact evaluations were started in five countries. The objectives of the Peru MCE were: (1) to document trends in IMCI implementation in the 24 departments of Peru from 1996 to 2000; (2) to document trends in indicators of health services coverage and impact (mortality and nutritional status) for the same period; (3) to correlate changes in these two sets of indicators, and (4) to attempt to rule out contextual factors that may affect the observed trends and correlations. An ecological analysis was performed in which the units of study were the 24 departments. By 2000, 10.2% of clinical health workers were trained in IMCI, but some districts showed considerably higher rates. There were no significant associations between clinical IMCI training coverage and indicators of outpatient utilization, vaccine coverage, mortality or malnutrition. The lack of association persisted after adjustment for several contextual factors including socioeconomic and environmental indicators and the presence of other child health projects. Community health workers were also trained in IMCI, and training coverage was not associated with any of the process or impact indicators, except for a significant positive correlation with mean height for age. According to the MCE impact model, IMCI implementation must be sufficiently strong to lead to an impact on health and nutrition. Health systems support for IMCI implementation in Peru was far from adequate. This finding, along with low training coverage level and a relatively low child mortality rate, may explain why the expected impact was not documented. Nevertheless, even districts with high levels of training coverage failed to show an impact. Further national effectiveness studies of IMCI and other child interventions are warranted as these interventions are scaled up.