Survey organisations often attempt to convert sample members who refuse to take part in a survey. Persuasive techniques are used in an effort to get the refusers to change their mind and agree to an interview. This is done in order to improve response rate and, possibly, to reduce non-response bias. However, refusal conversion attempts are expensive and must be justified. Previous studies of the effects of refusal conversion attempts are few and have been restricted to cross-sectional surveys. The criteria for success of a refusal conversion attempt are different in the case of a longitudinal survey, where for many purposes the researcher requires complete data over multiple waves. This paper uses data from the British Household Panel Survey (BHPS) from 1994 to 2002 to assess the long term effectiveness of refusal conversion procedures in terms of sample sizes, sample composition and data quality.