WALCOM 2010, the 4th International Workshop on Algorithms and Com- tation, held during February 10-12, 2010 in Dhaka, Bangladesh, covered the areas of approximation algorithms, combinatorial algorithms, combinatorial - timization, computational Biology, computational geometry, data structures, graph algorithms, graph drawing, parallel and distributed algorithms, par- eterized complexity, network optimization, online algorithms, randomized - gorithms and string algorithms. The workshop was organized jointly by the Bangladesh Academy of Sciences (BAS) and Bangladesh University of En- neering and Technology (BUET), and the quality of the workshop was ensured by a ProgramCommittee comprising 25 researchersof internationalrepute from Australia, Bangladesh, Canada, France, Germany, Greece, HongKong, Hungary, India, Italy, Japan, Switzerland, Taiwan, UK and USA. Thisvolumecontains23contributedpapersandfourinvitedpaperspresented atWALCOM2010.TheCallforPapersreceivedanenthusiasticresponse, resu- ing in 60 submissions from 21 countries. The Program Committee thoroughly reviewed each of the 60 submissions and accepted 23 of them for presentation in the workshop after elaborate discussions on review reports. The image of the workshopwas highly enhanced by the four invited talks of eminent and we- knownresearchersTetsuoAsanoofJAIST, Japan, SubirKumarGhoshofTIFR, India, Giuseppe Liotta of University of Perugia, Italy and J´ anos Pach of EPFL Lausanne, Switzerland and R´ enyi Institute Budapest, Hungary.