This study aimed to evaluate the impact of improved socio-economic conditions and health care on chronic mitral valve complications of rheumatic heart disease in Al Baha in the Kingdom of Saudi Arabia. Altogether, 190 cases of acute rheumatic fever (ARF) seen between 1982 and 1996 and 146 cases of symptomatic mitral stenosis seen between 1984 and 1996 were analysed. 2-D/Doppler echocardiography was used to evaluate the severity and progression of mitral regurgitation (MR)/mitral stenosis (MS). Of 90 cases of ARF who presented initially with MR, the murmur remained unchanged in 40%, increased in 30% and had decreased or disappeared in 30%. In cases with recurrence of ARF, mitral incompetence deteriorated in 16 of 26 cases (61.5%) and remained stable in ten (38%). Severe MS developed during follow-up in three cases of ARF, all aged less than 20 years. Seven of 50 cases (14%) of severe MS studied were aged 20 years or less. The 43% (25 of 58 cases) of severe cases of MS aged 20 years or less reported from King Faisal Hospital, Riyadh in 1981 compared with 14% of severe cases aged 20 years or less in this study indicates a significant slowing down of the rate of progression of MS following an attack of ARF in this region. Among individuals with MR during an ARF attack who reliably take their antibiotic prophylaxis, 70% will lose that murmur within 5 years of follow-up. In this series, only 30% showed a decrease or loss of MR and this probably reflects the degree of non-compliance with secondary antibiotic prophylaxis in our cases. The rate of default from antibiotic prophylaxis was 32.6%.