Inclusion Criteria:

- Age >18 years

- Histologically proven colorectal adenocarcinoma.

- Locally advanced (inoperable) or metastatic colorectal carcinoma treated with at
least one prior chemotherapy regimen.

- Progressive disease documented by CT either during or within 3 months of completion
of previous chemotherapy

- No previous malignant disease other than non-melanotic skin cancer or
carcinoma-in-situ of the uterine cervix.

- Unidimensional measurable disease as assessed by CT.

- Adequate bone marrow function; Hb >10g/dl, platelets >100 x109/l, WBC >3x109/l, Neut
>1.5x109/l.

- Adequate liver function: Serum Bilirubin <1.5 x upper limit of normal

- Adequate renal function: Serum Creatinine < 0.11 mmol/L

- No concurrent uncontrolled medical conditions

- WHO performance status 0,1 or 2

- Adequate contraceptive precautions, if appropriate

- Informed written consent

- Negative pregnancy test in women of child bearing age

- Life expectancy > 3 months

Exclusion Criteria:

- Medical or psychiatric condition that comprise the patient's ability to take informed
consent.

- Patients within 4 weeks of chemotherapy or radiotherapy (6 weeks for nitrosureas or
mitomycin C).

- Previous treatment with gemcitabine.

- Patients with uncontrolled cerebral metastases.