BACKGROUND Parvovirus B19 (PVB19) has been identified as the cause of erythema infectiosum. The epidemiology of PVB19 has not been extensively studied in Spain or in the autonomic community of Valencia. The aim of this work is to describe an outbreak of PVB19 infection occurring in the area of Monforte del Cid, Alicante. METHODS A probable case was defined as: all subjects living in Monforte who presented a rash (mainly facial) and/or arthralgia starting from November 1999. A confirmed case was defined as: a probable case confirmed by laboratory analysis or a case having an epidemiological link. Laboratory confirmation included specific IgG or IgM antibodies to PVB19. Cases were mainly detected through the Monforte del Cid Primary Health Care Center. RESULTS The outbreak occurred from November 1999 to August 2000. A total of 118 cases were detected, giving an overall attack rate (AR) of 23.2 cases per 1,000 inhabitants. The highest rates were in the age groups of 0-4 years old (AR 5 114.5 per 1,000) and 5-9 years old (AR 5 180.3 per 1,000). By gender, the AR per 1,000 inhabitants was 26.9 in men and 16.7 in women. Two of the cases were pregnant women and one of them had a miscarriage. CONCLUSIONS The outbreak of erythema infectiosum lasted 10 months and mainly affected children under 14 years old. Active surveillance was focussed on women in the first three months of pregnancy.