Screening for cancer is currently entering a very promising period as new technologies become available for assessment. However, this great opportunity also presents significant problems, starting with how do you select the likeliest method for evaluation? How do you do trials where the technology will be out-moded by the time the result is known? Indeed, how can all promising technologies be evaluated?There is a need for a renewal of methodological thinking on this topic at present. Randomised trials, which currently rely on death as the primary outcome, are very long and very complicated to undertake and run. There is an urgent need for biological markers, which are true surrogate end-points, to help reduce sample size and make trials more feasible, so that more trials can be done.For those screening modalities of demonstrated effectiveness, the key issue at present is how to maximise the outcome in population screening when the technology is transferred from the research setting to the public health setting. It is essential to remember that screening, per se, has never prevented a cancer nor prevented a cancer death. It is impossible to separate the issues of screening with those of adequate treatment: the best results in a screening programme will come when treatment is excellent.Screening is the first, and sometimes key, stage in a global management programme for the cancer in question. As the aim at present is to strive to maximise the effectiveness of population-based programmes, this aspect should be foremost in all thought processes.